A clock generator is a circuit that produces a timing signal (known as a clock signal) for use in synchronizing a circuit's operation. Clock generators are used in most electronic devices and their implementation can range from a simple crystal oscillator to complicated circuits.
A ring oscillator, an example of a clock generator, is a device composed of a chain of stages closed in a loop whose output oscillates between two voltage levels. The output levels may represent true and false in binary logic circuits. The stages of a ring oscillator may include inverters, differential buffers, and the like, and are typically attached in a chain. The output of the last stage is fed back into the first stage. The final output signal is asserted a finite amount of time after the first input is asserted. The feedback of this last output to the input causes the oscillation.
A ring oscillator typically requires only power to operate. Above a certain threshold voltage, oscillations begin spontaneously. To increase the frequency of oscillation, the applied voltage may be increased. This increases both the frequency of the oscillation and the power consumed, which is dissipated as heat. The dissipated heat may limit a speed of a particular ring oscillator. A size of the ring oscillator may also be used to affect its frequency. A smaller ring oscillator may result in a higher frequency of oscillation for a given power consumption.
Thus, it is with respect to these considerations and others that the present invention has been made.